The invention relates to a hard cutting insert for use in a roof drill bit that has a typical use of drilling boreholes in mine roofs. More particularly, the invention pertains to a hard cutting insert for use in a roof drill bit that exhibits an improvement in the performance of drilling boreholes in a roof bolting operation due to an improvement in drilling debris evacuation.
Expansion of an underground mine such as, for example, a coal mine, requires digging a tunnel. Initially this tunnel has an unsupported roof. In order to support and stabilize the roof in an established area in an underground tunnel, bore holes are drilled in the roof. The apparatus used to drill these holes comprises a drill with a long shaft, i.e., drill steel, attached to a drill bit. U.S. Pat. No. 6,533,049 to Rein, Sr., et al. and U.S. Pat. No. 6,598,688 to Wang each show a drill steel that is useful in a roof drill bit assembly for drilling such bore holes. U.S. Pat. No. 3,554,306 to Wilburn shows a drill rod assembly that is useful for drilling roof bolt bore holes.
A roof drill bit is detachably mounted, either directly or through the use of a chuck, to the drill steel at the distal end thereof. U.S. Pat. No. 5,927,411 to Sheirer and U.S. Pat. No. 5,833,017 to Woods et al. each show a roof drill bit assembly. To commence the drilling operation, the roof drill bit is then pressed against the roof and the drilling apparatus is operated so as to drill a bore hole in the roof. The bore holes may extend between two feet to greater than twenty feet into the roof. These bore holes are filled with resin and roof bolts are affixed within the bore holes. A roof support, such as roof panels, is then attached to the roof bolts.
As one can appreciate, the drilling operation generates drilling debris. It is important to remove this drilling debris from the vicinity of the borehole. More particularly, it is important to remove the drilling debris from the vicinity of where the hard cutting insert initially engages the earth strata so as to decrease wear on the hard cutting insert and increase the overall efficiency of the drilling operation.
Thus, it would be highly desirable to provide an improved hard cutting insert that better evacuates drilling debris during a drilling operation.